You can check detailed charts or buy specific sizes from major retailers: Hims Condom Size Guide for brand comparisons. Condomerie for measuring tips by nominal width.

Measure from the base (at the pubic bone) to the tip of the penis.

Wrap a piece of string or flexible measuring tape around the thickest part of the shaft.

It feels loose, slides around, or bunches up at the base. This increases the risk of slipping off .